One example of a harvester with rotary cutters is disclosed in U.S. Pat. No. 5,272,859 titled MECHANICAL DRIVE CENTER PIVOT MOWER CONDITIONER, which patent is owned by the assignee of the present invention. The harvesting machine disclosed in the '859 Patent is a pull-type harvester which requires the use of a separate tractor for towing the harvester through the field during use. The operating components of that harvester are mechanically driven through a drive line that is coupled with the power takeoff shaft of the towing tractor.
The harvester disclosed in the '859 Patent is also a conditioner, which means that the severed crop materials are passed between a pair of superimposed conditioning rolls before being discharged onto the ground. However, as a practical matter there is a limit to the length which such rolls can have and still function in an optimal manner. Thus, while the width of cut taken by a mower-conditioner using roll type conditioning mechanism can be made significantly wider than the length of the conditioning rolls, the crop that is severed by the machine must somehow be gathered inwardly after severance before being directed through the shorter conditioning rolls. Augers and other consolidating devices can be used behind the cutter bed for this purpose, but this adds an additional expense and subjects the crop materials to extra mechanical handling, which may be undesirable in many cases. The wider the cut, the more difficult the problem of conveying the severed outboard materials toward the center without using some kind of extra conveyor apparatus behind the cutters.
Furthermore, in making a longer cutter bed than disclosed in the '859 Patent wherein the endmost cutters are located at the opposite edges of a discharge opening to the conditioner rolls, additional engineering and expense is involved if the extra, added-on cutters are to be driven with their own extra spur gears within the gear case beneath the cutters. Thus, it would be of considerable benefit if additional cutters could be added onto the cutter bed without the need for adding additional internal gearing to the existing gear case. In that way, a standard, uniform size gear case could be used for both the standard length cutter bed and the extended length cutter bed having additional cutters.
Commercial hay producers typically use self-propelled machines and usually prefer a wider cutting width than that found on many pull-type units. Along with the extra width, however, comes increased loading on the power distribution drive in the gear case. Moreover, if a standard length gear case is to be utilized, some means must again be provided for extending driving power to additional cutters that are added on to extend the effective length of the cutter bed. Since in many instances the self-propelled tractors available for use with harvesters of this type are conventionally provided with engines capable of supplying pressurized hydraulic fluid for the operating components of a harvesting header, and since hydraulically powered machines are preferred in many instances by commercial operators, it would be desirable and beneficial to provide a hydraulic-driven cutter bed that would meet the needs and desires of commercial operators.